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1 /* Simple implementation of strstr for systems without it.
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2 This function is in the public domain. */
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3
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4 /*
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5
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6 @deftypefn Supplemental char* strstr (const char *@var{string}, const char *@var{sub})
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7
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8 This function searches for the substring @var{sub} in the string
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9 @var{string}, not including the terminating null characters. A pointer
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10 to the first occurrence of @var{sub} is returned, or @code{NULL} if the
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11 substring is absent. If @var{sub} points to a string with zero
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12 length, the function returns @var{string}.
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13
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14 @end deftypefn
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15
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16
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17 */
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18
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19
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20 /* FIXME: The above description is ANSI compiliant. This routine has not
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21 been validated to comply with it. -fnf */
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22
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23 #include <stddef.h>
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24
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25 extern char *strchr (const char *, int);
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26 extern int strncmp (const void *, const void *, size_t);
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27 extern size_t strlen (const char *);
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28
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29 char *
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30 strstr (const char *s1, const char *s2)
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31 {
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32 const char *p = s1;
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33 const size_t len = strlen (s2);
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34
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35 for (; (p = strchr (p, *s2)) != 0; p++)
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36 {
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37 if (strncmp (p, s2, len) == 0)
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38 return (char *)p;
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39 }
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40 return (0);
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41 }
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